Light carriers. Mothership Houshou and RJ who needs to prove herself to herself.
RJ was a decent carrier after her refit (believe it or not she was top heavy when completed), and could have been used as an exploitable carrier class under the Washington Treaty, but that loophole was plugged in the London Treaty before her completion. She carried about half the aircraft of the largest of the Japanese fleet carriers, which is respectable given her size. She was effective, even going on missions that Kaga could not due to Kaga's speed.
Houshou was always the too small to be used in combat prototype. She has far too few aircraft to be of much use in combat. 15 planes nominally. Good enough to maybe a small CAP force, or a dedicated attack squadron, but not both.
In contrast, the later cruiser hulled American Independence-class was a little bit faster than RJ, but carried less aircraft while being several thousand tons heavier. The American light carriers were typically used as a dedicated CAP carrier for the fleet while attached to two fleet carriers who would be the strike force. In addition the Independence-class also typically carried a small strike force to be used to exploit opportunities or for scouting.
USS Langley (CV-1), had better numbers of planes than Houshou, but was way, way too slow. After the Lexingtons were finished and Ranger was started, the Americans didn't build light carrier until the war, and by then were using cruiser hulls or made escort carrier out of transports and oiler based hulls, which were mostly slower than Houshou, but could carry more heavier aircraft.
It's also cool that they're the only ones of their class, are around the same size with Ryuujou being slightly bigger than Houshou, and are practically senior carriers.
